Police officers need a warrant to search a cell phone unless which conditions are met?

The requirement for a warrant to search a cell phone can be bypassed under exigent circumstances. This legal doctrine allows law enforcement to act without a warrant when there are immediate dangers that necessitate swift action. Such circumstances might include situations where evidence may be destroyed or when there is a risk to officer or public safety that requires immediate access to information on a device.

For example, if officers are pursuing a suspect who they believe has a cell phone containing key evidence and they fear that the suspect may erase the data or that critical information could be lost due to the immediate risk of destruction, they may search the phone without a warrant. This is rooted in the understanding that certain situations demand urgent responses and adherence to warrant requirements may impede effective law enforcement actions in those specific instances.

The other conditions provided in the options do not hold the same legal weight in the context of warrantless searches of cell phones as exigent circumstances do.